Pairing and Superconductivity Driven by Strong Quasiparticle Renormalization in Two-Dimensional Organic Charge Transfer Salts

Li, Jun; Schmalian, Joerg; Trivedi, Nandini

doi:10.1103/physrevlett.94.127003

Cited by 81 publications

(111 citation statements)

References 40 publications

(66 reference statements)

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“…The resulting Luttinger surface renormalizes to perfect nesting. A similar behavior has been observed in recent variational studies of organic charge transfer-salt superconductors (24). At half-filling the Hubbard model reduces to a spin model with NN J ϭ 4t 2 ͞U and a frustrating next NN JЈ ϭ 4(tЈ) 2 ͞U.…”

Section: Fs Renormalizationsupporting

confidence: 51%

Determining the underlying Fermi surface of strongly correlated superconductors

Gros

Edegger

Muthukumar

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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The notion of a Fermi surface (FS) is one of the most ingenious concepts developed by solid-state physicists during the past century. It plays a central role in our understanding of interacting electron systems. Extraordinary efforts have been undertaken, by both experiment and theory, to reveal the FS of the high-temperature superconductors, the most prominent class of strongly correlated superconductors. Here, we discuss some of the prevalent methods used to determine the FS and show that they generally lead to erroneous results close to half-filling and at low temperatures, because of the large superconducting gap (pseudogap) below (above) the superconducting transition temperature. Our findings provide a perspective on the interplay between strong correlations and superconductivity and highlight the importance of strong coupling theories for the characterization and determination of the underlying FS in angle-resolved photoemission spectroscopy experiments.strong correlation ͉ renormalized mean-field theory ͉ high-temperature superconductors D uring the last decade, angle-resolved photoemission spectroscopy (ARPES) has emerged as a powerful tool (1, 2) for studying the electronic structure of the high-temperature superconductor (HTSC) (3). ARPES is a direct method for probing the Fermi surface (FS), the locus in momentum space where the one-electron excitations are gapless (4). However, because the low-temperature phase of the HTSC has a superconducting or pseudogap with d-wave symmetry, a FS can be defined only along the nodal directions or along the so-called Fermi arcs (1, 2, 5-7). The full ''underlying FS'' emerges only when the pairing interactions are turned off, either by a Gedanken experiment or by raising the temperature. Its experimental determination presents a great challenge because ARPES is more accurate at lower temperatures. Because the FS plays a key role in our understanding of condensed matter, it is important to know what is exactly measured by ARPES in a superconducting or a pseudogap state. The problem becomes even more acute in HTSC because of the presence of strong correlation effects (8 -11). Hence, it is desirable to examine a reference d-wave superconducting state with aspects of strong correlation built explicitly in its construction. Motivated by these considerations, we study the FS of a strongly correlated d-wave superconductor (8, 11) and discuss our results in the context of ARPES in HTSC. Fermi vs. Luttinger SurfaceWe begin by highlighting the differences between a FS and a Luttinger surface. The FS is determined by the poles of the one-electron Green's function (4). The Luttinger surface is defined as the locus of points in reciprocal space, where the one-particle Green's function changes sign (12). In the Fermi liquid state of normal metals, the Luttinger surface coincides with the FS. In a Mott-Hubbard insulator the Green's function changes sign because of a characteristic 1͞ divergence of the single-particle self-energy (13, 14) at momenta k of the noninteracting FS. In ...

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Section: Fs Renormalizationsupporting

confidence: 51%

Determining the underlying Fermi surface of strongly correlated superconductors

Gros

Edegger

Muthukumar

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…It is well known that the perfect nesting of the square lattice means that is insulating for arbitrarily small U/t. For t = t, it is found, numerically, that the Mott transition occurs at around U/t = 10-15, depending on the method used [3,[15][16][17][18][19][20][21]79]. The metal-insulator transition line in Fig.…”

Section: Comparison With Organicsmentioning

confidence: 99%

“…This model contains three parameters: U the effective on-site Coulomb repulsion, t the nearest-neighbor hopping integral, and t the next-nearest-neighbor hopping integral along one diagonal only. The Hubbard model on the anisotropic triangular lattice has been studied via a number of approaches [15][16][17][18][19][20][21]. Some methods have suggested that a spin liquid is realized in the insulating phase.…”

Section: Introductionmentioning

confidence: 99%

“…However, later numerical work [52] has shown that the ground state has "120 • order"-a special case of spiral order, discussed below, with an ordering wave vector Q = (2π/3,2π/3). A range of other methods have been used to study the Heisenberg model on the anisotropic triangular lattice including linear spin-wave theory [53,54], modified spin-wave theory [55], series expansions [12,56], the coupled cluster method [57], large-N expansions [58], variational Monte Carlo [59], resonating valence bond theory [15,19,[60][61][62], pseudofermion functional renormalization group [63], slave rotor theory [64], renormalization group [65], and the density matrix renormalization group [66]. These calculations show that for small J /J , Néel (π,π) order is realised and spiral (q,q) long-range AFM order is realized for J /J ∼ 1.…”

Section: Introductionmentioning

confidence: 99%

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Spin-liquid phase due to competing classical orders in the semiclassical theory of the Heisenberg model with ring exchange on an anisotropic triangular lattice

2014

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We investigate the effect of ring exchange on the ground-state properties and magnetic excitations of the S = 1/2 Heisenberg model on the anisotropic triangular lattice with ring exchange at T = 0 using linear spin-wave theory. Classically, we find stable Néel, spiral and collinear magnetically ordered phases. Upon including quantum fluctuations to the model, linear spin-wave theory shows that ring exchange induces a large quantum disordered region in the phase diagram, completely wiping out the classically stable collinear phase. Analysis of the spin-wave spectra for each of these three models demonstrates that the large spin-liquid phase observed in the full model is a direct manifestation of competing classical orders. To understand the origin of these competing phases, we introduce models where either the four spin contributions from ring exchange, or the renormalization of the Heisenberg terms due to ring exchange are neglected. We find that these two terms favor rather different physics.

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“…Quantum Monte Carlo calculations [8] find enhanced dSC correlations. Ground state wave-functions obtained from variational methods [9] predict a transition between a dSC and a spin liquid phase, akin to a Mott transition, in the highly frustrated case. The spin liquid phase was also predicted by variational methods, and through a gauge theory of the Hubbard model [10].…”

mentioning

confidence: 99%

Antiferromagnetism and Superconductivity in Layered Organic Conductors: Variational Cluster Approach

Sahebsara

Sénéchal

2006

Phys. Rev. Lett.

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The κ-(ET)2X layered conductors (where ET stands for BEDT-TTF) are studied within the dimer model as a function of the diagonal hopping t ′ and Hubbard repulsion U . Antiferromagnetism and d-wave superconductivity are investigated at zero temperature using variational cluster perturbation theory (V-CPT). For large U , Néel antiferromagnetism exists for t ′ < t ′ c2 , with t ′ c2 ∼ 0.9. For fixed t ′ , as U is decreased (or pressure increased), a d x 2 −y 2 superconducting phase appears. When U is decreased further, the a dxy order takes over. There is a critical value of t ′ c1 ∼ 0.8 of t ′ beyond which the AF and dSC phases are separated by Mott disordered phase.The proximity of antiferromagnetism (AF) and d-wave superconductivity (dSC) is a central and universal feature of high-temperature superconductors, and leads naturally to the hypothesis that the mechanisms behind the two phases are intimately related. This proximity is also observed in the layered organic conductor κ-(ET) 2 Cu-[N(CN) 2 ]Cl, an antiferromagnet that transits to a superconducting phase upon applying pressure[1] (here ET stands for BEDT-TTF). Other compounds of the same family, κ-(ET) 2 Cu(NCS) 2 and κ-(ET) 2 Cu[N(CN) 2 ]Br, are superconductors with a critical temperature near 10K at ambient pressure. However, another member of this family, κ-(ET) 2 Cu 2 (CN) 3 , displays no sign of AF order, but becomes superconducting upon applying pressure [2,3]. The character of the superconductivity in these compounds is still controversial. While many experiments indicate that the SC gap has nodes (presumably d-wave), others are interpreted as favoring a nodeless gap. The literature on the subject is rich, and we refer to a recent review article[4] for references.The interplay of AF and dSC orders, common to both high-T c and κ-ET materials, cannot be fortuitous and must be a robust feature that can be captured in a simple model of these strongly correlated systems. κ-ET compounds consist of orthogonally aligned ET dimers that form conducting layers sandwiched between insulating polymerized anion layers. The simplest theoretical description of these complex compounds is the so-called dimer Hubbard model [5,6] (Fig. 1A) in which a single bonding orbital is considered on each dimer, occupied by one electron on average, with the Hamiltonianwhere c rσ (c † rσ ) creates an electron (hole) at dimer site r on a square lattice with spin projection σ, and n rσ =c † rσ c rσ is the hole number operator. rr ′ ([rr ′ ]) indicates nearest-(next-nearest)-neighbor bonds. As the ratio t ′ /t grows from 0 towards 1, Néel AF is increasingly

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Pairing and Superconductivity Driven by Strong Quasiparticle Renormalization in Two-Dimensional Organic Charge Transfer Salts

Cited by 81 publications

References 40 publications

Determining the underlying Fermi surface of strongly correlated superconductors

Determining the underlying Fermi surface of strongly correlated superconductors

Spin-liquid phase due to competing classical orders in the semiclassical theory of the Heisenberg model with ring exchange on an anisotropic triangular lattice

Antiferromagnetism and Superconductivity in Layered Organic Conductors: Variational Cluster Approach

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